Taxes change at least annually and sometime even during a year.  Being up to date on the latest changes for both actual tax returns and for tax planning is critical to clients.   To stay knowledgeable, I belong to professional organizations that publish newletters and bulletins to keep tax professionals informed.  Also every year I include my staff in attending  an update seminar to go further in depth on all the changes that have been implemented for the upcoming year.  Not only is it helpful to know these things to prepare taxes, it definitely helps to let clients know you care about them and want them to be on top of their tax situations.